The separation in time is so vast (age of cosmos vs age of civs) that the most probable contact would be ancient ruins. Probably so old and bizarre that nobody would realize for years that there was anything even there.
Also, this guy: http://en.wikipedia.org/wiki/Heinrich_Schliemann
According to ancient texts, "Many eldritch abominations just couldn't seem to die off, and have been locked away in a vault never to be exposed in large population centers again by any means. For the love of our God(s), don't try to translate
ANY of the content within, you have been warned. Societies have collapsed under the influence of these things. The fact you found it in such a hellish environment should be hint enough how dangerous these things are, and that it's not as much a time capsule, rather than has been an attempt to destroy it, and has somehow failed. We apologize for our mistakes as a sentient race with the contents within."
Contents within the vault:
-The complete Jersey Shore Collection and anything with any of the members involved
-All of MTV after it jumped the shark and TRL was no longer cool (after it's first season)
-The complete "I Love the ___'s" series (Don't use this for historical reference.), and anything from VH1 past Year 2000, when they stopped caring about music
-The complete Seltzer & Friedberg collection
-All "Reality TV" ever created, including the originator "The Real World" Season 1
-Toddlers & Tiaras, Dance Moms, and anything similar in nature as a "Documentary" to avoid the "Reality TV" radar
-The secret recipe of the McRib sandwich
-The Twilight Saga, 50 Shades of Grey, and any other "romance novel" ever created
-The entire Scientology "Religious" Doctrines (AKA- The 'Cult of Sirius' documents (SEE: XCOM Apocalypse))
-Text message archive of anytime post-20th century (Madness ensues after stupid people got hold of fast messaging.)
-Facebook and Myspace, and the recipes for social media
...The list goes on.
One last thing, it reads: "In honor of a show that was good to watch, 'Futurama', please refer to the contents of this package, and the era they come from, as "The Time Capsule of 'The Stupid Ages'". Thank you."